Indlela yokukhetha iihenjisi ezikumgangatho ophezulu? I-1 surface Material yeyona nto ibaluleke kakhulu echaphazela ihenjisi. Ihenjisi ekhutshwe ngentsimbi yodidi oluphezulu ithe tyaba kwaye igudile, inesandla esithambileyo, esityebileyo kwaye esilinganayo, kunye nombala othambileyo. Kodwa intsimbi engaphantsi, ngokucacileyo inokubona umphezulu orhabaxa, ongalinganiyo,